The invention relates generally to improving efficiency of network resource usage in call sessions.
Various different types of communications networks enable call sessions between end points, such as telephones, computer systems fitted with voice processing capabilities, and other devices. Generally, two types of networks exist: circuit-switched networks and packet-based networks. In a circuit-switched network, a dedicated, end-to-end circuit connection is established for the duration of each call. This works well for communications that are generally continuous, such as speech between two end users.
Packet-based networks, on the other hand, communicate by use of packets sent in a series of bursts. The packets are generally communicated when needed, without an explicit connection defined between the two end points. Instead, routing is based on addresses carried in the packets. Examples of packet-based networks include Internet Protocol (IP) networks, which employ connectionless internetwork layers. In a connectionless packet-based network, packets or other units of data are injected into the network, which packets travel independently over any path (and possibly over different paths) to a destination point. The packets may even arrive out of order. Another type of packet-based data network is a connection-oriented network, such as an Asynchronous Transfer Mode (ATM) network or Frame Relay network. In a connection-oriented packet-based network, a virtual circuit or connection is established between two end points, and packets are received in the same order in which they were transmitted.
Protocols employed in circuit-switched networks for communications include the Integrated Services Digital Network (ISDN), which is a network service that provides end-to-end digital connectivity to support a wide range of services, including voice and non-voice services. Another type of circuit-switched network is the T-carrier network, such as the T-1 or T-3 network. A T-1 network is a digital network capable of carrying 24 channels multiplexed to create an aggregate bandwidth of 1.536 megabits per second (Mbps).
In many of the digital circuit-switched networks, time-division multiplexing (TDM) is used to merge multiple data streams onto different time slots of a circuit. Using TDM, each terminal is assigned a time slot (or plural time slots) for communications over a circuit. When a call over a TDM circuit is initiated, a time slot is reserved to dedicate the time slot for the voice channel. Once reserved, the TDM time slot remains idle if unused by the requesting device.
With the availability of various different types of communications networks, interworking is performed to enable communications between the different types of networks. Thus, for example, a media gateway may be provided between a circuit-switched network and a packet-based network. A call may be originated from a terminal connected to a circuit-switched network with the destination being a terminal connected to another circuit-switched network, and with the two circuit-switched networks connected by a packet-based network. The call is translated in the gateways between circuit-switched and packet-based formats. Typically, on both the circuit-switched and packet-based networks, the gateways perform the necessary exchanges of messaging to establish call sessions on the respective circuit-switched and packet-based networks. The necessary resources are reserved on both the circuit-switched and packet-based networks.
In contrast to circuit-switched networks such as TDM networks, a resource being reserved on a packet-based network does not necessarily mean it is consumed. An unused resource on a packet-based network, although reserved, remains available for use by other devices. However, once a gateway establishes a bearer traffic connection between the TDM side and the packet-based side, the reserved resources on the packet-based network are consumed even before the call is fully established since the idle time slots on the TDM network are communicated over the packet-based network. As a result, unnecessary consumption of packet-based network resources may occur.
A need thus exists for an improved method and apparatus of utilizing network resources in a call session.
In general, according to one embodiment, a method of establishing a call session over a first network of a first type and a second network of a second type, the method comprising receiving a call request over the first network and establishing a call over the second network. The method waits for a success indication of the call over the second network before connecting the first network to the second network for the call session to delay consumption of a resource on the second network.
Some embodiments of the invention may have one or more of the following advantages. By waiting for a success indication of the call over the second network before connecting the first network to the second network, more efficient usage of resources on the second network can be achieved. For example, if the first network utilizes a time-division multiplexing (TDM) scheme, reserving a time slot makes that time slot unavailable for other network elements on the first network; instead, the time slot remains idle. If the first and second networks are connected too early, then resources on the second network are consumed by unnecessarily communicating the idle time slots of the first network onto the second network. By reducing resource consumption on the second network, such resources remain available for other communications sessions over the second network.
Other features and advantages will become apparent from the following description, from the drawings, and from the claims.